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This >>> disables >>> reader and writer optimistic lock spinning and stealing. >>> >>> Now if a non-first writer in the queue is somehow woken up or first >>> entering the waiting loop, it can't acquire the lock.  This is not >>> the case before that commit as the writer that set the handoff bit >>> will clear it when exiting out via the out_nolock path. This is less >>> efficient as the busy rwsem stays in an unlock state for a longer time. >>> >>> This patch allows a non-first writer to ignore the handoff bit if it >>> is not originally set or initiated by the first waiter. >>> >>> Fixes: d257cc8cb8d5 ("locking/rwsem: Make handoff bit handling more >>> consistent") >> >> Hi Waiman, >> >> 1. You likely need : >> >> Cc: >> >> Since d257cc8cb8d5 has been migrated to other LTS threads (5.15.y for >> sure) . > > Since the commit has a fixes tag, the stable will automatically pick it up. > >> >> 2. I had posted this earlier: >> >> [PATCH 5.15 1/1] Revert "locking/rwsem: Make handoff bit handling more >> consistent" >> >> That is likely not needed now. > Right. The patch was created to fix a problem reported by another user. > So reverting it may not the right move. Thanks for the quick follow up. >> >> >> 3. Please add : >> >> Reported-by: Jorge Lopez >> >> We can likely test this, but I can't give a ETA when that will happen. >> >> >>> Signed-off-by: Waiman Long >> >> Acked-by: John Donnelly > > Will add the that when I send out the next version. > > Cheers, > Longman >